This species is best known as a primary pathogen on kiwifruit (Actinidia deliciosa) in Rio Grande do Sul and Santa Catarina, Brazil (Ferreiraet al. 2017; Oliveira et al. 2021; Piveta et al. 2016). However, Actinidia appears to be highly susceptible to Ceratocystis species, and isolates of C. manginecans (Eucalyptus-type strains) and the following new specieswere also associated with Ceratocystis wilt on kiwifruitand shown to be pathogenic to this host (Ferreira et al.2017; Oliveira et al. 2021; Piveta et al. 2016). Variation in microsatellite markers suggested that the C. alfenasii population on Actinidia in Rio Grande do Sul was native to the area (Ferreira et al. 2017). Ceratocystis alfenasii also causes a wilt on yerba mate trees (Ilex paraguariensis) in plantations in Rio Grande do Suland Paraná (Brito et al. 2021; Santos et al. 2018). Melo et al. (2016) reported the fungus causing blackrot in corms of yellow potato (Arracacia xanthorhiza) in Minas Gerais. Isolates from these three unrelatedhosts were interfertile in crossing studies (TABLE 2), and they grouped closely in the phylogenetic analysis of MAT sequences, which placed C. alfenasii outside of the South American and Caribbean subclades of the LAC (FIG. 1). No distinguishing morphological features were noted in C. alfenasii isolates compared with other LAC species.

BRAZIL. RIO GRANDE DO SUL:Farroupilha, from Actinidia deliciosa, Jul 2010,G. Piveta (holotype ISC 455943). Ex-type culture URMICRO 11731 = C3666 = PM20.